Electrophotographic devices, such as laser printers, utilize heat to fuse toner to paper to provide printed images. For example, a fuser of the printer is provided by a nip defined by one or a pair of heated rollers. As the print media, typically paper, is passed through the rollers, toner corresponding to the indicia to be printed is melted and fused with the fibers in the paper. During printing operations substantial heat is generated and it is important to control the temperature of the interior of the printer. Cooling fans are typically employed to circulate air through the printer to control the temperature of the interior of the printer.
Laser printers typically include a computerized printer engine that controls the operation of all aspects of the printer. The printer engine typically includes a fan control unit as a subpart thereof. Typically, the fan control unit utilizes a fan control program that selects a low fan speed when the printer is idle and a higher fan speed when the printer is in use. This manner of fan speed control needs improvement, particularly as the fan speeds are selected for worst case conditions, but for minimal printing operations, these speeds result in undesirable and unnecessary noise.
The present invention relates to an improved control system for a laser printer. The control system utilizes a control program which is preferably incorporated into the computer code of the printer engine and facilitates selection of multiple sets of fan speeds based on the actual degree of usage of the printer, as opposed to a constant set of predetermined speeds corresponding to “printing” and “idle” conditions as is utilized in conventional control systems.
In this manner, the invention enables improved control over the operation of printer cooling fans without the need for additional sensors or other equipment. This advantageously provides more customized control of fan speed and avoids unnecessary noise often associated with printer fans operating at a higher than necessary speed during minimal printing operations.